Wheel and tire assembly

ABSTRACT

A wheel assembly includes a rigid wheel and an airless flexible tire with certain performance characteristics of a pneumatic tire. The rigid wheel includes a central portion and a plurality of circumferentially spaced mounting elements removably attached to a radially outer margin of the central portion. The tire is mounted on the wheel and engages the mounting elements such that portions of the tire not engaging the mounting elements are separated radially from the wheel by a space. The tire is configured such that portions of the tire not engaging the mounting elements flex inwardly toward the wheel when subject to ground engaging pressure, thereby minimizing ground penetration and soil disruption. The tire may include one or more tension elements embedded in the tire to increase the tire&#39;s strength and resilience.

RELATED APPLICATIONS

The present application is a continuation application and claimspriority of co-pending application titled “WHEEL AND TIRE ASSEMBLY”,Ser. No. 15/016,023, filed Feb. 4, 2016, which was issued as U.S. Pat.No. 9,889,705 on Feb. 13, 2018, and is a continuation application andclaims priority to previously co-pending application titled “WHEEL ANDTIRE ASSEMBLY”, Ser. No. 13/654,691, filed Oct. 18, 2012, which wasissued as U.S. Pat. No. 9,283,810 on Mar. 15, 2016, the content of whichis hereby incorporated by reference in its entirety.

BACKGROUND 1. Field

Embodiments of the present invention relate to wheel and tire assembliesfor use with airless tires. More particularly, embodiments of thepresent invention relate to wheel assemblies with airless tirespresenting certain performance characteristics of pneumatic tires.

2. Related Art

Irrigation systems include elevated water conduits supported by mobiletowers. Such mobile towers are mounted on wheels that propel the towersalong the ground to be irrigated. The wheels typically include pneumatictires that require periodic maintenance, including adjusting airpressure, repairing tires that develop holes or other damage, andreplacing old or damaged tires that are beyond repair.

Because irrigation systems and similar agricultural equipment aretypically used in fields or other remote locations, monitoring the tiresfor problems and reaching the tires to perform maintenance and repairscan be inconvenient or difficult. If a tire loses air pressure and isnot repaired in a timely manner, damage to the tire, to the equipmentmounted on the tire, or both may result.

One solution to the challenges presented by the use of pneumatic tiresinvolves using wheels without tires. While this approach addresses mostof the problems of tire maintenance, repair and replacement, it presentsother challenges. Tireless wheels, for example, are rigid and experiencegreater ground penetration than a flexible tire, thereby creating rutsor otherwise disturbing the land more than a pneumatic tire. Similarproblems exist for tractors, automobiles, and other vehicles thattypically use pneumatic tires.

Accordingly, there is a need for a solution which overcomes thelimitations described above.

SUMMARY

Embodiments of the present invention solve the above-described problemsby providing a wheel assembly including an airless tire with someperformance characteristics of a pneumatic tire.

A wheel assembly in accordance with an embodiment of the inventionbroadly comprises a rigid wheel and a flexible airless tire. The rigidwheel includes a central portion and a plurality of circumferentiallyspaced mounting elements removably attached to a radially outer marginof the central portion. The tire is mounted on the wheel and engages themounting elements such that portions of the tire not engaging themounting elements are separated radially from the wheel by a space, theportions of the tire not engaging the mounting elements being configuredto flex inwardly toward the wheel when subject to ground engagingpressure.

A method of assembling a wheel assembly in accordance with anotherembodiment of the invention comprises removably fastening a firstplurality of mounting elements to a radially outer margin of a firstaxial side of a central portion of a wheel such that the mountingelements are spaced circumferentially around the central portion of thewheel. The wheel is placed in an airless tire such that each of thefirst plurality of mounting elements engages an inner surface of theairless tire. A second plurality of mounting elements are removablyfastened to a radially outer margin of a second axial side of thecentral portion of the wheel such that each of the second plurality ofmounting elements engages the inner surface of the airless tire. Thesecond plurality of mounting elements are also spaced circumferentiallyaround the central portion of the wheel.

A wheel assembly in accordance with yet another embodiment of theinvention comprises a rigid wheel and an airless flexible tire mountedon the wheel. The wheel includes a disc shaped central portion with aplurality of circumferentially spaced flanges corresponding to aradially outer margin of the central portion. A pair of mountingelements is removably attached to each of the flanges such that each ofthe mounting element pairs includes a first mounting element removablyattached to a first side of the flange and a second mounting elementremovably attached to a second side of the flange opposite the firstside of the flange. The pair of mounting elements presents an elongated,transversely oriented radially outer edge.

The tire engages the outer edges of the mounting elements such thatportions of the tire not engaging the mounting elements are separatedradially from the wheel by a space. The portions of the tire notengaging the mounting elements are configured to flex inwardly towardthe wheel when subject to ground engaging pressure. A tension element isembedded in the tire and extends longitudinally around the tire.

This summary is provided to introduce a selection of concepts in asimplified form that are further described below in the detaileddescription. This summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Other aspectsand advantages of the present invention will be apparent from thefollowing detailed description of the preferred embodiments and theaccompanying drawing figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary irrigation system includingwheel assemblies constructed in accordance with embodiments of theinvention;

FIG. 2 is a front side perspective view of one of the wheel assembliesof FIG. 1, the wheel assembly including a rigid wheel and a flexibleairless tire mounted on the wheel;

FIG. 3 is a rear side perspective view of the wheel assembly of FIG. 2;

FIG. 4 is an exploded view of the wheel assembly of FIG. 2;

FIG. 5 is a fragmentary partially exploded view of the wheel assembly ofFIG. 2;

FIG. 6 is fragmentary partially exploded view of the wheel assembly ofFIG. 2;

FIG. 7 is a fragmentary, cross-sectional view of the wheel assembly ofFIG. 2; and

FIG. 8 is an environmental side elevation view of the wheel assembly ofFIG. 2 illustrating the wheel assembly mounted on the irrigation systemof FIG. 1 and engaging the ground.

The drawing figures do not limit the present invention to the specificembodiments disclosed and described herein. The drawings are notnecessarily to scale, emphasis instead being placed upon clearlyillustrating the principles of the invention.

DETAILED DESCRIPTION

The following detailed description references the accompanying drawingsthat illustrate specific embodiments in which the invention may bepracticed. The embodiments are intended to describe aspects of theinvention in sufficient detail to enable those skilled in the art topractice the invention. Other embodiments can be utilized and changescan be made without departing from the scope of the present invention.The following detailed description is, therefore, not to be taken in alimiting sense. The scope of the present invention is defined only bythe appended claims, along with the full scope of equivalents to whichsuch claims are entitled.

In this description, references to “one embodiment”, “an embodiment”, or“embodiments” mean that the feature or features being referred to areincluded in at least one embodiment of the technology. Separatereferences to “one embodiment”, “an embodiment”, or “embodiments” inthis description do not necessarily refer to the same embodiment and arealso not mutually exclusive unless so stated and/or except as will bereadily apparent to those skilled in the art from the description. Forexample, a feature, structure, act, etc. described in one embodiment mayalso be included in other embodiments, but is not necessarily included.Thus, the present technology can include a variety of combinationsand/or integrations of the embodiments described herein.

Turning now to the drawing figures, and initially FIG. 1, an exemplaryirrigation system 10 is illustrated including a plurality of wheelassemblies constructed in accordance with embodiments of the invention.The illustrated irrigation system 10 is a central pivot irrigationsystem that broadly comprises a fixed central pivot 12 and a mainsection 14 pivotally connected to the central pivot 12. The irrigationsystem 10 may also comprise an extension arm (also commonly referred toas a “swing arm” or “corner arm”) pivotally connected to the free end ofthe main section.

The fixed central pivot 12 may be a tower or any other support structureabout which the main section 14 may pivot. The central pivot 12 hasaccess to a well, water tank, or other source of water and may also becoupled with a tank or other source of agricultural products to injectfertilizers, pesticides and/or other chemicals into the water forapplication during irrigation.

The main section 14 may comprise a number of mobile support towers16A-D, the outermost 16D of which is referred to herein as an “endtower”. The support towers are connected to the fixed central pivot 12and to one another by truss sections 18A-D or other supports to form anumber of interconnected spans. The irrigation system 10 illustrated inFIG. 1 includes four mobile support towers 16A-D; however, it maycomprise any number of mobile support towers without departing from thescope of the present invention.

Each mobile tower may include a drive tube 20A-D on which a pair ofwheel assemblies 22A-D is mounted. Embodiments of the wheel assemblies22A-D are described in more detail below. A drive motor 24A-D is mountedto each drive tube 20A-D for driving the wheel assemblies 22A-D. Themotors 24A-D may include integral or external relays so they may beturned on, off, and reversed. The motors may also have several speeds orbe equipped with variable speed drives.

Each of the truss sections 18A-D carries or otherwise supports a conduitsection 26A-D or other fluid distribution mechanism that is connected influid communication with all other conduit sections. A plurality ofsprinkler heads, spray guns, drop nozzles, or other fluid-emittingdevices are spaced along the conduit sections 26A-D to apply waterand/or other fluids to land underneath the irrigation system.

The irrigation system 10 may also include an optional extension arm (notshown) pivotally connected to the end tower 16D and supported by a swingtower with steerable wheels driven by a motor. The extension arm may bejoined to the end tower by an articulating pivot joint. The extensionarm is folded inward relative to the end tower when it is not irrigatinga corner of a field and may be pivoted outwardly away from the end towerwhile irrigating the corners of a field.

The irrigation system 10 may also include one or more high pressuresprayers or end guns 28 mounted to the end tower 16D or to the end ofthe extension arm. The end guns 28 may be activated at the corners of afield or other designated areas to increase the amount of land that canbe irrigated.

It will be appreciated that the irrigation system 10 is illustrated anddescribed herein as one exemplary implementation of the wheel assemblies22 described in detail below. Other, equally preferred implementationsof the wheel assemblies 22 not shown or discussed in detail herein mayinclude, without limitation, other types of irrigation systems, such aslateral irrigation systems, other types of agricultural equipment, suchas wagons, carts, implements, and so forth, or other types of vehiclessuch as buses, trucks, and automobiles. However, embodiments of theinvention are especially suited for irrigation systems and othervehicles or systems that travel over un-paved or un-finished ground.

Referring now to FIGS. 2-8, a wheel assembly 22 constructed inaccordance with embodiments of the invention is illustrated. The wheelassembly 22 broadly includes a rigid wheel 30 and a flexible airlesstire 32 mounted on the wheel 30 in a generally circumscribingrelationship to the wheel 30. The wheel 30 and the tire 32 areconfigured such that the tire 32, while being airless, has somecharacteristics of a pneumatic tire that improve the performance of thetire. For example, the wheel 30 and tire 32 are configured such thatportions of the tire 32 flex radially inwardly toward the wheel 30 inresponse to ground engaging pressure, as illustrated in FIG. 8. It willbe appreciated that this flexing action increases the total groundengaging footprint of the wheel assembly 22, thus distributing theweight of the wheel assembly 22 and the weight of any machinerysupported by the wheel assembly 22 over a larger area and limiting thetotal amount of ground penetration of the wheel assembly 22.Additionally, ground penetration of traction lugs or otherground-gripping elements of the tire 32 is limited, as explained belowin greater detail.

As used herein, “ground engaging pressure” refers to pressure exerted onthe wheel assembly 22 by the ground when the wheel assembly 22 is atrest on the ground or rolling on the ground. Ground engaging pressuremay include pressure exerted on the wheel assembly 22 from differentdirections or from multiple directions simultaneously, such as where thewheel assembly 22 is on inclined terrain or rolling over an obstacle.Ground engaging pressure is related to the weight of the wheel assembly22 and to the weight of any machinery supported by the wheel assembly22, and thus will vary from one embodiment of the invention to anotherand from one implementation to another.

The wheel 30 is configured to engage the tire 32 at circumferentiallyspaced locations such that portions of the tire 32 between the points ofengagement flex radially inwardly in response to ground engagingpressure. In the illustrated embodiment, the wheel 30 includes a discshaped inner central portion 34 and a plurality of circumferentiallyspaced mounting elements 36 removably attached to a radially outermargin of the central portion 34. The central portion 34 of the wheel 30includes an innermost hub 38 with a plurality of apertures for attachingto, for example, lug nuts or similar attachment components.

The radially outer margin of the central portion 34 of the wheel 30defines a plurality of flanges 40 that extend radially outwardly andsupport the mounting elements 36, as explained below in greater detail.Each of the flanges 40 presents a trapezoidal shape that narrows from abroader inner portion 42 to a narrower outer portion 44. Each of theflanges 40 includes a plurality of apertures for use in securing themounting elements 36 to the flanges 40. In the illustrated embodiment,the apertures are configured to receive bolts that secure the mountingelements 36 to the flanges 40. In the illustrated embodiment, the wheel30 includes ten flanges 40 spaced circumferentially around the wheel 30.

A pair of mounting elements 36 is removably attached to each of theflanges 40. Each of the mounting element pairs includes a first mountingelement 36 removably attached to a first side of the flange 40 and asecond mounting element 36 removably attached to a second side of theflange 40 opposite the first side of the flange 40. When mounted on theflange 40, the pair of mounting elements 36 presents an elongated,transversely oriented radially outer edge 46 that extends radiallybeyond the flange 40 and engages the tire 32. As illustrated, the outeredge 46 comprises two segments, a first segment 46 a corresponding to afirst mounting element 36 and a first axial side of the outer edge 46,and a second segment 46 b corresponding to a second mounting element 36and a second axial side of the outer edge 46. The segments 46 a, 46 bmay be separated to define a space 48 between the segments 46 a, 46 b,which engages a portion 49 of the tire 32 between the mounting elements36 to prevent the tire 32 from shifting laterally relative to the wheel30, as explained below.

As used herein, the mounting elements 36 are “removably attached” to thecentral portion 34 of the wheel 30 if the mounting elements 36 can beseparated from the central portion 34 and reattached without altering ordamaging the structure of the mounting elements 36 or the centralportion 34 of the wheel 30. In the illustrated embodiment, the mountingelements 36 are removably attached to the central portion 34 of thewheel 30 using nut and bolt combinations that can be removed andreplaced to remove and replace the mounting elements 36. By way ofexample, mounting elements that are integrally formed with, or weldedto, the central portion 34 of the wheel 30 are not removably attached.

Each mounting element 36 includes a pair of mounting flanges 50 a,b, anouter edge portion 52 and web portions 54 a,b connecting each of themounting flanges 50 a,b with the outer edge portion 52. The mountingflanges 50 a,b are each rectangular and correspond to side margins ofthe mounting element 36. Each of the mounting flanges 50 a,b is flat,connected to one of the web portions 54 a,b along a longitudinal edge ofthe flange 50 a,b, and positioned at an angle of approximately ninetydegrees relative to one of the web portions 54 a,b. The first webportion 54 a and the second web portion 54 b are connected at the outeredge portion 52 and diverge from the outer edge portion 52 at an angleof approximately thirty degrees. Each web portion 54 a,b presents atriangular shape.

Each mounting element 36 may be constructed of a single, unitary pieceof material, such as metal, folded or otherwise formed to the desiredshape and configuration. Furthermore, all of the mounting elements 36may be identical in size and shape. By way of example, each of themounting elements 36 may be constructed by cutting a piece of metal to aparticular flat shape and then forming the piece of metal to the desiredshape through a series of bending steps.

The mounting element 36 pairs are approximately equally spaced aroundthe central portion 34 of the wheel 30 and extend radially outwardlyfrom the central portion 34. When the tire 32 is mounted on the wheel 30the mounting elements 36 engage portions of the tire 32 such that thetire 32 is separated radially from the central portion 34 of the wheel30 by a space, allowing portions of the tire 32 to flex inwardly towardthe central portion 34 in response to ground engaging pressure. As usedherein, the mounting elements 36 extend radially outwardly from thecentral portion 34 if at least a portion of each of the mountingelements 36 extends radially outwardly from the central portion 34 ofthe wheel 30.

In the illustrated embodiment, the wheel assembly 22 includes tenmounting element pairs approximately equally spaced around the radiallyouter margin of the central portion 34 of the wheel 30. The mountingelements 36 are positioned on the wheel 30 such that each mountingelement pair defines an elongated radially outer edge 46 that isoriented transversely on the wheel 30, that is, oriented parallel withthe axis of rotation of the wheel assembly 22. The mounting element 36pairs engage the tire and the total transverse length of each of theouter edges 46 is approximately equal to a width of the tire 32.

If the wheel 30 includes ten mounting element 36 pairs (as illustrated),the angular separation of the mounting element 36 pairs is approximatelythirty-six degrees. Thus, if the wheel 30 is about forty-eight inches indiameter, the mounting element 36 pairs are spaced approximately twelveand one-half inches apart. If the wheel 30 is about fifty inches indiameter, the mounting element 36 pairs are spaced approximatelythirteen inches apart. If the wheel 30 is about twenty-four inches indiameter, the mounting element 36 pairs are spaced approximately sixinches apart.

The tire 32 is configured to be mounted on the wheel 30 such that atleast a portion of the tire 32 engages the mounting elements 36 and thetire 32 presents a generally circular or nearly circular outer profile.Advantageously, the wheel 30 is configured for use with an airless tire.As used herein, a “tire” is a flexible component positioned andconfigured to engage the ground during use of the wheel assembly 22. An“airless tire” is a tire that does not require trapped or compressed airfor normal and proper use. An airless tire may be constructed of asingle, unitary piece of material or multiple pieces of material. Asexplained above and illustrated in FIG. 8, the tire 32 is configured toflex inwardly in response to ground engaging pressure. As used herein,the tire 32 can “flex” if it can deflect or bend repeatedly and returnto its original shape.

The illustrated tire 32 includes a body 56 that is generally cylindricalin shape with a plurality of traction lugs 58 extending radiallyoutwardly from an outer side of the body 56 and a plurality of drivelugs 60 extending radially inwardly from an inner side of the body 56.In the illustrated embodiment, the outer side 62 of the tire body 56 isgenerally transversely flat, that is, the outer side of the bodypresents little or no curvature from a first edge to a second edge ofthe tire. Similarly, the inner side 64 of the tire body 56 is alsogenerally transversely flat.

The traction lugs 58 engage the ground and help prevent the wheelassembly 22 from slipping relative to the ground. The illustratedtraction lugs 58 are generally rectangular in shape and transverselyoriented on the tire 32, are integrally formed with the tire 32 and maybe approximately equally spaced circumferentially around the outer side62 of the tire body 56. As illustrated in FIG. 8, the tire 32 may beconfigured such that the traction lugs 58 are positioned intermediatethe mounting elements 36. This configuration allows the portion of thetire 32 bearing the traction lug 58 to flex inwardly in response toground engaging pressure. This performance characteristic allows eachtraction lug 58 to engage the ground, yet limits the amount of groundpenetration and soil disturbance. It may be desirable in someimplementations to position the traction lugs 58 proximate or in directradial alignment with the mounting elements 36. Such alternativeconfigurations of the tire 32 are within the ambit of the presentinvention.

As illustrated in FIG. 8, certain traction lugs 58 b may be larger(i.e., have a greater radial reach) than other traction lugs 58 a. Inthe illustrated embodiment, one of every three traction lugs has agreater radial reach, corresponding to a position that is approximatelyhalf the distance between consecutive mounting element 36 pairs. Thus,there are three traction lugs between consecutive mounting element 36pairs, with the middle traction lug being larger than the other two.

The drive lugs 60 engage the wheel 30 and prevent the tire 32 fromshifting longitudinally or laterally on the wheel 30. In the illustratedembodiment, the drive lugs 60 are arranged in pairs corresponding to themounting elements 36 such that the drive lugs 60 are adjacent themounting elements 36 on opposite sides of the mounting elements 36. Eachof the drive lugs 60 is integrally formed in the tire 32 and presents agenerally elongated body with a cross member (portion 49 of the tire 32)connecting each drive lug 60 pair. Each of the cross members is locatedat a center of the tire 32 and corresponds to the space 48 betweenmounting elements 36.

The tire 32 is constructed of a flexible material, such as rubber, PVCor plastic. The tire 32 may be configured such that as the tire flexesinwardly toward the wheel 30, the flexed portion of the tire 32 remainstransversely flat or substantially transversely flat. This may bedesirable, for example, to preserve a wide footprint or otherwise limitthe amount of ground penetration. With particular reference to FIGS.5-7, one or more tension elements 66 a,b may be secured to the tire 32to give the tire 32 added structural strength and resilience. As usedherein, a tension element 66 a,b is “secured to” the tire 32 if it ispartially or completely embedded in the tire 32 or otherwise attached tothe tire 32. A first tension element 66 a may be placed in a first axialside of the tire body 56 and a second tension element 66 b may be placedin a second axial side of the tire body 56. Alternatively, a singletension element may be located in a central portion of the tire 32. Thetension elements 66 a,b are preferably completely embedded in the tire32, as illustrated.

The tension elements 66 a,b are preferably more resilient than thematerial used to construct the tire 32 such that the one or more tensionelements 66 a,b increase the overall resilience of the tire 32,strengthening the structure of the tire 32 and enabling the tire 32 toreturn to its original shape after being subject to deflection duringuse. The one or more tension elements 66 a,b may be constructed ofmetal, such as spring steel, or other resilient and durable material.More particularly, each of the tension elements 66 a,b may be a metalband constructed of a solid piece of metal or of multiple bonded orbraided metal elements. The tension elements 66 a,b may present a widththat is between 0.05 and 0.5 times a total width of the tire, such as0.1, 0.2 or 0.3 times the total width of the tire. If the tire 32 istwelve inches wide, for example, each of the tension elements 66 a,b maybe about two or two and one-half inches wide and between one-eighth andone-half of an inch thick.

The wheel 30 is constructed of a rigid material such as, for example,metal, plastic or a composite material. The size of the wheel assembly22 may vary substantially from one embodiment of the invention toanother without departing from the scope of the invention. Dimensionsand ranges of various preferred embodiments will now be discussed withthe understanding that the dimensions and ranges are exemplary, and notlimiting, in nature. The diameter of the wheel 30 is preferably withinthe range of from about twenty-four inches to about sixty inches andmore preferably within the range of from about thirty-six inches toabout forty-eight inches. The width of the wheel 30 (i.e., the totalwidth of each of the mounting element pairs) is preferably within therange of from about six inches to about eighteen inches and morepreferably within the range of from about eight inches to about sixteeninches. The diameter of central portion 34 of the wheel 30 is preferablybetween about 0.6 and 0.9 times the total diameter and may particularlybe about 0.8 times the total diameter.

The height of the flanges 40 (i.e., the distance from the inner portion42 to the outer portion 44) is preferably within the range of from aboutthree inches to about seven inches, more preferably within the range offrom about four inches to about six inches, and may particularly beabout five inches. The length of the inner portion 42 of each flange 40is preferably within the range of from about five inches to about teninches, more preferably within the range of from about six inches toabout nine inches, and may be about seven inches, about seven andone-half inches, or about eight inches. The length of the outer portion44 of each flange 40 is preferably within the range of from about twoinches to about seven inches, more preferably within the range of fromabout three inches to about six inches, and may be about four inches,about four and one-half inches, or about five inches.

The thickness of the tire body 56 is preferably within the range of fromabout one-half inch to about three inches, more preferably within therange of from about one inch to about two inches. The height of thetraction lugs 58 is preferably within the range of from aboutone-quarter inch to about four inches, more preferably within the rangeof from about one-half inch to about three inches. In one exemplaryembodiment, the wheel assembly 22 is about eleven inches wide and aboutfifty-two inches in diameter. The tire body preferably presents a widthto thickness ratio of between five and twenty.

Although the invention has been described with reference to theexemplary embodiments illustrated in the attached drawings, it is notedthat equivalents may be employed and substitutions made herein withoutdeparting from the scope of the invention as recited in the claims. Forexample, while the embodiment of the invention illustrated and describedabove includes ten pairs of mounting elements 36, a different number ofmounting element 36 pairs may be used without departing from the scopeof the invention. Additionally, the particular structure andconfiguration of each of the mounting elements 36 may vary from oneembodiment of the invention to another without departing from the scopeof the invention.

Having thus described various embodiments of the invention, what isclaimed as new and desired to be protected by Letters Patent includesthe following:
 1. A wheel assembly comprising: a rigid wheel including—a central portion having a plurality of apertures for attachingfasteners thereto, and a plurality of circumferentially spaced mountingelements configured to be removably attached to the central portion viafasteners so that each of the mounting elements is prevented fromrotating relative to the central portion; and an airless flexible tirethat does not include air during normal use mounted on the rigid wheel,portions of the tire extending at least six (6) inches annularly betweenthe mounting elements and not engaging the mounting elements beingcompletely separated radially from the rigid wheel by a through-spacetransversely extending entirely from a first axial side of the tire toan opposite axial side of the tire, the portions of the tire notengaging the mounting elements being configured to flex radiallyinwardly toward the rigid wheel when subject to ground engagingpressure.
 2. The wheel assembly of claim 1, wherein the central portionincludes a first side and a second side opposite the first side, theplurality of mounting elements including a plurality of mounting elementpairs, each mounting element pair including a first mounting elementremovably attached to the first side of the central portion of the rigidwheel and a second mounting element removably attached to the secondside of the central portion of the rigid wheel opposite the firstmounting element.
 3. The wheel assembly of claim 2, each pair ofmounting elements presenting an elongated, transversely oriented outeredge configured to engage the tire.
 4. The wheel assembly of claim 3, afirst axial side of the outer edge corresponding to the first mountingelement, a second axial side of the outer edge corresponding to thesecond mounting element and being separated from the first axial side bya space, the tire including a radially inwardly-extending flangeconfigured to be positioned between the first and second sides of theouter edge.
 5. The wheel assembly of claim 1, the central portion of therigid wheel being constructed of a single, unitary piece of material. 6.The wheel assembly of claim 1, the tire including a pair of drive lugspositioned to engage opposite sides of one of the mounting elements, thedrive lugs extending radially inwardly from the tire.
 7. The wheelassembly of claim 1, the tire including a plurality of traction lugsextending radially outwardly from the tire.
 8. The wheel assembly ofclaim 7, wherein the traction lugs are positioned annularly intermediatethe mounting elements.
 9. The wheel assembly of claim 1, wherein theairless flexible tire further includes one or more tension elements atleast partially embedded therein.
 10. The wheel assembly of claim 1,wherein each mounting element is a single, unitary piece of material.11. The wheel assembly of claim 1, wherein the central portion furtherincludes a plurality of flanges extending radially outwardly forsupporting the mounting elements.
 12. The wheel assembly of claim 11,wherein the plurality of flanges each have a trapezoidal shape thatnarrows from a broader inner portion to a narrower outer portion.
 13. Amethod of assembling a wheel assembly, the method comprising: removablyfastening a first plurality of mounting elements to a radially outermargin of a first axial side of a wheel, the mounting elements beingspaced at least six (6) inches circumferentially around the wheel;placing the wheel in an airless tire that does not include air duringnormal use such that each mounting element of the first plurality ofmounting elements engages an inner surface of the airless tire; andremovably fastening a second plurality of mounting elements to aradially outer margin of a second axial side of the wheel such that thefirst plurality of mounting elements and second plurality of mountingelements are prevented from rotating relative to the central portion andan elongated outer edge of each of the second plurality of mountingelements aligns with an outer edge of one of the first plurality ofmounting elements so that each of the second plurality of mountingelements engage the inner surface of the airless tire, the secondplurality of mounting elements being spaced circumferentially around thewheel, portions of the tire positioned annularly between the mountingelements and not engaging the mounting elements being completelyseparated radially from the wheel by a through-space transverselyextending entirely from a first axial side of the tire to an oppositeaxial side of the tire and portions of the tire not engaging themounting elements being configured to flex radially inwardly toward thewheel when subject to ground engaging pressure when the wheel assemblyis assembled.
 14. The method of claim 13, the wheel being constructed ofa single, unitary piece of material and each of the mounting elementsbeing constructed of a single, unitary piece of material, each of themounting elements being identical to all of the other mounting elements.15. The method of claim 13, wherein the outer edge of the first andsecond plurality of mounting elements engage a plurality of drive lugsextending radially inwardly from the inner surface of the airless tire.16. The method of claim 13, further comprising laterally aligningportions of the tire with spaces extending between mounting elements ofthe first plurality of mounting elements and mounting elements of thesecond plurality of mounting elements.
 17. A mobile support structurewith at least one wheel assembly attached thereto, the wheel assemblycomprising: a rigid wheel including— a central portion, and a pluralityof circumferentially spaced mounting elements removably attached to aradially outer margin of the central portion; and an airless flexibletire mounted on the wheel, the airless flexible tire including aplurality of drive lug pairs, each pair of drive lugs being positionedto engage opposite sides of one of the mounting elements, the drive lugsextending radially inwardly from the tire, portions of the tireextending annularly between the mounting elements and not engaging themounting elements being completely separated radially from the wheel bya through-space transversely extending entirely from a first axial sideof the tire to an opposite axial side of the tire, the portions of thetire not engaging the mounting elements being configured to flexradially inwardly toward the wheel when subject to ground engagingpressure.
 18. The mobile support structure of claim 17, wherein themobile support structure is a mobile support tower of a movableirrigation system.
 19. The mobile support structure of claim 17, whereinthe mobile support structure is part of an agricultural vehicle.
 20. Themobile support structure of claim 17, the central portion of the wheelbeing constructed of a single, unitary piece of material, and each ofthe mounting elements being constructed of a single, unitary piece ofmaterial and being identical to all of the other mounting elements. 21.A wheel assembly comprising: a rigid wheel including— a central portionhaving a plurality of apertures for attaching fasteners thereto, and aplurality of circumferentially spaced mounting elements configured to beremovably attached to the central portion via fasteners so that each ofthe mounting elements is prevented from rotating relative to the centralportion; and an airless flexible tire that does not include air duringnormal use mounted on the rigid wheel, portions of the tire extendingbetween the mounting elements and not engaging the mounting elementsbeing completely separated radially from the rigid wheel by athrough-space transversely extending entirely from a first axial side ofthe tire to an opposite axial side of the tire, the portions of the tirenot engaging the mounting elements being configured to flex radiallyinwardly toward the rigid wheel when subject to ground engagingpressure.